The present invention relates to a printing mode control system for controlling a system including a plurality of printers differing from each other in print dot density connected thereto.
In most cases, an impact wire dot printer and a non-impact page printer are connected to a system capable of being connected to a plurality of printers differing from each other in print dot density. Generally, the print dot density of the wire dot printer is low, for example, 1/180 in. in dot pitch, due to its structural characteristics, while the print dot density of the non-impact page printer is very high, for example, 1/240 in. in dot pitch. Accordingly, when a page printer for fine dot matrix print is connected to a system which has also been connected to a wire dot printer for coarse dot matrix print, or when the wire dot printer is disconnected from the system and the page printer is connected to the system, problems arise a that the print size of characters is reduced according to the increase in print dot density and in that the printing area is reduced according to the increase in print dot density.
The foregoing problems of the conventional system will be explained more concretely with reference to FIGS. 1(a) and 1(b) showing an exemplary mode of reduction of a character, and FIGS. 2(a) and 2(b) showing an exemplary mode of reduction of a printing area.
The most preferable size of letters, from the viewpoint of readability, is in the 9 to 10 point range (1 point = 0.3514 mm, JIS Z 8305). Generally, a character (font) comprises a 22.times.22 dot matrix (approximately 3.1 mm .times. 3.1 mm = 8.8 point) or a 24.times.24 dot matrix (approximately 3.4 mm .times. 3.4 mm = 9.6 point) when the print dot pitch is 1/180 in. When a 9.6-point character of the 24.times.24 dot matrix for a wire dot printer having a 1/180 in. dot pitch as shown in FIG. 1(a) is printed by a page printer having a 1/240 in dot pitch, the 9.6-point character is reduced to a 7.2-point character (approximately 2.54 mm .times. 2.54 mm), which makes reading the character very difficult. Furthermore, suppose that the wire dot printer having a 1/180 in dot pitch prints characters of an mxn dot matrix on a sheet in a print layout as shown in FIG. 2(a), in which character pitch X and line pitch Y are expressed by EQU X=1/180(in.).times.m(dot).times.a EQU Y=1/180(in.).times.n(dot).times.b
where a and b are integral multiples of character size, the page printer having the 1/240 in dot pitch then prints the same characters in an unsatisfactory print layout as shown in FIG. 2(b) deteriorating the layout of print area. In FIG. 2(b), character pitch X' and line pitch Y' are expressed by EQU X'=1/240(in.).times.m(dot).times.a=0.75X EQU Y'=1/240(in.).times.n(dot).times.b=0.75Y
where m, n, a and b are the same as mentioned above.
In a printing mode control system compensating for such drawbacks, the application program or the like stored in a host unit is provided with an individual print data for a printer using a coarse dot matrix, an individual print data for a printer using a fine dot matrix, and control programs respectively for controlling those printers. For example, the application program of the host unit is provided with a down-line load font using a 24.times.24 dot matrix for the wire dot printer having the 1/180 in dot pitch, and a down-line load font using a dot matrix of 32.times.32 for the page printer of 1/240 in. in dot pitch, and registers the down-line load font conforming to the mode of operation of the printer to be controlled among those down-line load fonts.
However, such a printing mode control system, in which the application program in the host unit includes an individual print data for the printer using a coarse dot matrix, an individual print data for the printer using a fine dot matrix, and control programs respectively for controlling those printers, requires a complex application program, and inevitably requires a new application program or reconstruction of the existing application program when connecting an additional printer using a different dot matrix to the system which has been in operation in a previously constructed printing mode control system with a printer using a dot matrix.